import math
a, b, c, d = map(float, input().split())
s1 = (a - c) * (a - c)
s2 = (b - d) * (b - d)
print("%.6f"%math.sqrt(s1+s2))
 import math math a, b, c, d = map(float, input().split()) a map(float, input().split()) map float input().split() ().split () input split b c d s1 = (a - c) * (a - c) s1 (a - c) * (a - c) a - c a c a - c a c s2 = (b - d) * (b - d) s2 (b - d) * (b - d) b - d b d b - d b d print("%.6f"%math.sqrt(s1+s2)) print "%.6f"%math.sqrt(s1+s2) "%.6f" math.sqrt(s1+s2) math.sqrt math sqrt s1+s2 s1 s2 a, b, c, d = map(float, input().split()) map(float, input().split()) a b, c, d = map(float, input().split()) map(float, input().split()) b c, d = map(float, input().split()) map(float, input().split()) c s2 = (b - d) * (b - d) (b - d) * (b - d) s2 s1 = (a - c) * (a - c) (a - c) * (a - c) s1 d = map(float, input().split()) map(float, input().split()) d
import math
a, b, c, d = map(float, input().split())
s1 = (a - c) * (a - c)
s2 = (b - d) * (b - d)
print("%.6f"%math.sqrt(s1+s2))

